mirror of
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basic apu support (copy from CryBoy w/ slight modification), scheduler short-circuit, scheduler clear
This commit is contained in:
Matthew Berry
parent
70913a4ee8
commit
ac8319b19c
10 changed files with 776 additions and 11 deletions
182
src/crab/apu.cr
Normal file
182
src/crab/apu.cr
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@ -0,0 +1,182 @@
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require "./apu/abstract_channels" # so that channels don't need to all import
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require "./apu/*"
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lib LibSDL
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fun queue_audio = SDL_QueueAudio(dev : AudioDeviceID, data : Void*, len : UInt32) : Int
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fun get_queued_audio_size = SDL_GetQueuedAudioSize(dev : AudioDeviceID) : UInt32
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fun clear_queued_audio = SDL_ClearQueuedAudio(dev : AudioDeviceID)
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fun delay = SDL_Delay(ms : UInt32) : Nil
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end
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class APU
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CHANNELS = 2 # Left / Right
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BUFFER_SIZE = 1024
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SAMPLE_RATE = 32768 # Hz
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SAMPLE_PERIOD = CPU::CLOCK_SPEED // SAMPLE_RATE
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FRAME_SEQUENCER_RATE = 512 # Hz
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FRAME_SEQUENCER_PERIOD = CPU::CLOCK_SPEED // FRAME_SEQUENCER_RATE
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@sound_enabled : Bool = false
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@buffer = Slice(Float32).new BUFFER_SIZE
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@buffer_pos = 0
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@frame_sequencer_stage = 0
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getter first_half_of_length_period = false
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# @left_enable = false
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# @left_volume = 0_u8
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# @right_enable = false
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# @right_volume = 0_u8
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@left_enable = true
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@left_volume = 7_u8
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@right_enable = true
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@right_volume = 7_u8
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# @nr51 : UInt8 = 0x00
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@nr51 : UInt8 = 0xFF
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@audiospec : LibSDL::AudioSpec
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@obtained_spec : LibSDL::AudioSpec
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def initialize(@gba : GBA)
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@audiospec = LibSDL::AudioSpec.new
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@audiospec.freq = SAMPLE_RATE
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@audiospec.format = LibSDL::AUDIO_F32SYS
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@audiospec.channels = CHANNELS
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@audiospec.samples = BUFFER_SIZE
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@audiospec.callback = nil
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@audiospec.userdata = nil
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@obtained_spec = LibSDL::AudioSpec.new
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@channel1 = Channel1.new @gba
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@channel2 = Channel2.new @gba
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@channel3 = Channel3.new @gba
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@channel4 = Channel4.new @gba
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tick_frame_sequencer
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get_sample
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raise "Failed to open audio" if LibSDL.open_audio(pointerof(@audiospec), pointerof(@obtained_spec)) > 0
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LibSDL.pause_audio 0
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end
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def tick_frame_sequencer : Nil
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@first_half_of_length_period = @frame_sequencer_stage & 1 == 0
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case @frame_sequencer_stage
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when 0
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@channel1.length_step
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@channel2.length_step
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@channel3.length_step
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@channel4.length_step
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when 1 then nil
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when 2
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@channel1.length_step
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@channel2.length_step
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@channel3.length_step
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@channel4.length_step
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@channel1.sweep_step
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when 3 then nil
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when 4
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@channel1.length_step
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@channel2.length_step
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@channel3.length_step
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@channel4.length_step
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when 5 then nil
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when 6
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@channel1.length_step
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@channel2.length_step
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@channel3.length_step
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@channel4.length_step
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@channel1.sweep_step
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when 7
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@channel1.volume_step
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@channel2.volume_step
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@channel4.volume_step
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else nil
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end
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@frame_sequencer_stage = 0 if (@frame_sequencer_stage += 1) > 7
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@gba.scheduler.schedule FRAME_SEQUENCER_PERIOD, ->tick_frame_sequencer
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end
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def get_sample : Nil
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channel1_amp = @channel1.get_amplitude
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channel2_amp = @channel2.get_amplitude
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channel3_amp = @channel3.get_amplitude
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channel4_amp = @channel4.get_amplitude
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@buffer[@buffer_pos] = (@left_volume / 7).to_f32 *
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((@nr51 & 0x80 > 0 ? channel4_amp : 0) +
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(@nr51 & 0x40 > 0 ? channel3_amp : 0) +
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(@nr51 & 0x20 > 0 ? channel2_amp : 0) +
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(@nr51 & 0x10 > 0 ? channel1_amp : 0)) / 4
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@buffer[@buffer_pos + 1] = (@right_volume / 7).to_f32 *
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((@nr51 & 0x08 > 0 ? channel4_amp : 0) +
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(@nr51 & 0x04 > 0 ? channel3_amp : 0) +
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(@nr51 & 0x02 > 0 ? channel2_amp : 0) +
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(@nr51 & 0x01 > 0 ? channel1_amp : 0)) / 4
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@buffer_pos += 2
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# push to SDL if buffer is full
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if @buffer_pos >= BUFFER_SIZE
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while LibSDL.get_queued_audio_size(1) > BUFFER_SIZE * sizeof(Float32) * 2
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LibSDL.delay(1)
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end
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LibSDL.queue_audio 1, @buffer, BUFFER_SIZE * sizeof(Float32)
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@buffer_pos = 0
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end
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@gba.scheduler.schedule SAMPLE_PERIOD, ->get_sample
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end
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def read_io(index : Int) : UInt8
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case index
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when @channel1 then @channel1.read_io index
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when @channel2 then @channel2.read_io index
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when @channel3 then @channel3.read_io index
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when @channel4 then @channel4.read_io index
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when 0xFF24
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((@left_enable ? 0b10000000 : 0) | (@left_volume << 4) |
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(@right_enable ? 0b00001000 : 0) | @right_volume).to_u8
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when 0xFF25 then @nr51
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when 0xFF26
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0x70 |
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(@sound_enabled ? 0x80 : 0) |
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(@channel4.enabled ? 0b1000 : 0) |
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(@channel3.enabled ? 0b0100 : 0) |
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(@channel2.enabled ? 0b0010 : 0) |
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(@channel1.enabled ? 0b0001 : 0)
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else 0xFF
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end.to_u8
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end
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# write to apu memory
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def write_io(index : Int, value : UInt8) : Nil
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return unless @sound_enabled || index == 0x84 || Channel3::WAVE_RAM_RANGE.includes?(index)
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case index
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when @channel1 then @channel1.write_io index, value
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when @channel2 then @channel2.write_io index, value
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when @channel3 then @channel3.write_io index, value
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when @channel4 then @channel4.write_io index, value
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when 0xFF24
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@left_enable = value & 0b10000000 > 0
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@left_volume = (value & 0b01110000) >> 4
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@right_enable = value & 0b00001000 > 0
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@right_volume = value & 0b00000111
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when 0xFF25 then @nr51 = value
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when 0x84
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if value & 0x80 == 0 && @sound_enabled
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(0xFF10..0xFF25).each { |addr| self.write_io addr, 0x00 }
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@sound_enabled = false
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elsif value & 0x80 > 0 && !@sound_enabled
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@sound_enabled = true
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@frame_sequencer_stage = 0
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@channel1.length_counter = 0
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@channel2.length_counter = 0
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@channel3.length_counter = 0
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@channel4.length_counter = 0
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end
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end
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end
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end
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98
src/crab/apu/abstract_channels.cr
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98
src/crab/apu/abstract_channels.cr
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@ -0,0 +1,98 @@
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# All of the channels were developed using the following guide on gbdev
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# https://gbdev.gg8.se/wiki/articles/Gameboy_sound_hardware
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abstract class SoundChannel
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property enabled : Bool = false
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@dac_enabled : Bool = false
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# NRx1
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property length_counter = 0
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# NRx4
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@length_enable : Bool = false
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def initialize(@gba : GBA)
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end
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# Step the channel, calling helpers to reload the period and step the wave generation
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def step : Nil
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step_wave_generation
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schedule_reload frequency_timer
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end
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# Step the length, disabling the channel if the length counter expires
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def length_step : Nil
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if @length_enable && @length_counter > 0
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@length_counter -= 1
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@enabled = false if @length_counter == 0
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end
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end
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# Used so that channels can be matched with case..when statements
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abstract def ===(value) : Bool
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# Calculate the frequency timer
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abstract def frequency_timer : UInt32
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abstract def schedule_reload(frequency_timer : UInt32) : Nil
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# Called when @period reaches 0
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abstract def step_wave_generation : Nil
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abstract def get_amplitude : Float32
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abstract def read_io(index : Int) : UInt8
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abstract def write_io(index : Int, value : UInt8) : Nil
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end
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abstract class VolumeEnvelopeChannel < SoundChannel
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# NRx2
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@starting_volume : UInt8 = 0x00
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@envelope_add_mode : Bool = false
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@period : UInt8 = 0x00
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@volume_envelope_timer : UInt8 = 0x00
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@current_volume : UInt8 = 0x00
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@volume_envelope_is_updating = false
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def volume_step : Nil
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if @period != 0
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@volume_envelope_timer -= 1 if @volume_envelope_timer > 0
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if @volume_envelope_timer == 0
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@volume_envelope_timer = @period
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if (@current_volume < 0xF && @envelope_add_mode) || (@current_volume > 0 && !@envelope_add_mode)
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@current_volume += (@envelope_add_mode ? 1 : -1)
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else
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@volume_envelope_is_updating = false
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end
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end
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end
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end
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def init_volume_envelope : Nil
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@volume_envelope_timer = @period
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@current_volume = @starting_volume
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@volume_envelope_is_updating = true
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end
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def read_NRx2 : UInt8
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@starting_volume << 4 | (@envelope_add_mode ? 0x08 : 0) | @period
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end
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def write_NRx2(value : UInt8) : Nil
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envelope_add_mode = value & 0x08 > 0
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if @enabled # Zombie mode glitch
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@current_volume += 1 if (@period == 0 && @volume_envelope_is_updating) || !@envelope_add_mode
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@current_volume = 0x10_u8 - @current_volume if (envelope_add_mode != @envelope_add_mode)
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@current_volume &= 0x0F
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end
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@starting_volume = value >> 4
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@envelope_add_mode = envelope_add_mode
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@period = value & 0x07
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# Internal values
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@dac_enabled = value & 0xF8 > 0
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@enabled = false if !@dac_enabled
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end
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end
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144
src/crab/apu/channel1.cr
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144
src/crab/apu/channel1.cr
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@ -0,0 +1,144 @@
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class Channel1 < VolumeEnvelopeChannel
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WAVE_DUTY = [
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[0, 0, 0, 0, 0, 0, 0, 1], # 12.5%
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[1, 0, 0, 0, 0, 0, 0, 1], # 25%
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[1, 0, 0, 0, 0, 1, 1, 1], # 50%
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[0, 1, 1, 1, 1, 1, 1, 0], # 75%
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]
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RANGE = 0x60..0x67
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def ===(value) : Bool
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value.is_a?(Int) && RANGE.includes?(value)
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end
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@wave_duty_position = 0
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# NR10
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@sweep_period : UInt8 = 0x00
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@negate : Bool = false
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@shift : UInt8 = 0x00
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@sweep_timer : UInt8 = 0x00
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@frequency_shadow : UInt16 = 0x0000
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@sweep_enabled : Bool = false
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@negate_has_been_used : Bool = false
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# NR11
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@duty : UInt8 = 0x00
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@length_load : UInt8 = 0x00
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# NR13 / NR14
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@frequency : UInt16 = 0x00
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def step_wave_generation : Nil
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@wave_duty_position = (@wave_duty_position + 1) & 7
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end
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def frequency_timer : UInt32
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(0x800_u32 - @frequency) * 4 * 4
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end
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def schedule_reload(frequency_timer : UInt32) : Nil
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@gba.scheduler.schedule frequency_timer, ->step, Scheduler::EventType::APUChannel1
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end
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def sweep_step : Nil
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@sweep_timer -= 1 if @sweep_timer > 0
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if @sweep_timer == 0
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@sweep_timer = @sweep_period > 0 ? @sweep_period : 8_u8
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if @sweep_enabled && @sweep_period > 0
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calculated = frequency_calculation
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if calculated <= 0x07FF && @shift > 0
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@frequency_shadow = @frequency = calculated
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frequency_calculation
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end
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end
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end
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end
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def get_amplitude : Float32
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if @enabled && @dac_enabled
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dac_input = WAVE_DUTY[@duty][@wave_duty_position] * @current_volume
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dac_output = (dac_input / 7.5) - 1
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dac_output
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else
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0
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end.to_f32
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end
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# Calculate the new shadow frequency, disable channel if overflow 11 bits
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# https://gist.github.com/drhelius/3652407#file-game-boy-sound-operation-L243-L250
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def frequency_calculation : UInt16
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calculated = @frequency_shadow >> @shift
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calculated = @frequency_shadow + (@negate ? -1 : 1) * calculated
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@negate_has_been_used = true if @negate
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@enabled = false if calculated > 0x07FF
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calculated
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end
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def read_io(index : Int) : UInt8
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case index
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when 0x60 then 0x80_u8 | @sweep_period << 4 | (@negate ? 0x08 : 0) | @shift
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when 0x62 then 0x3F_u8 | @duty << 6
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when 0x63 then read_NRx2
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when 0x64 then 0xFF_u8 # write-only
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when 0x65 then 0xBF_u8 | (@length_enable ? 0x40 : 0)
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else raise "Reading from invalid Channel1 register: #{hex_str index.to_u16}"
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end
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end
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def write_io(index : Int, value : UInt8) : Nil
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case index
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when 0x60
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@sweep_period = (value & 0x70) >> 4
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@negate = value & 0x08 > 0
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@shift = value & 0x07
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# Internal values
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@enabled = false if !@negate && @negate_has_been_used
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when 0x61 # not used
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when 0x62
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@duty = (value & 0xC0) >> 6
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@length_load = value & 0x3F
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# Internal values
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@length_counter = 0x40 - @length_load
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when 0x63
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write_NRx2 value
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when 0x64
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@frequency = (@frequency & 0x0700) | value
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when 0x65
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@frequency = (@frequency & 0x00FF) | (value.to_u16 & 0x07) << 8
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length_enable = value & 0x40 > 0
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# Obscure length counter behavior #1
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if @gba.apu.first_half_of_length_period && !@length_enable && length_enable && @length_counter > 0
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@length_counter -= 1
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@enabled = false if @length_counter == 0
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end
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@length_enable = length_enable
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trigger = value & 0x80 > 0
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if trigger
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@enabled = true if @dac_enabled
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# Init length
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if @length_counter == 0
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@length_counter = 0x40
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# Obscure length counter behavior #2
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@length_counter -= 1 if @length_enable && @gba.apu.first_half_of_length_period
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end
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# Init frequency
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@gba.scheduler.clear Scheduler::EventType::APUChannel1
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schedule_reload frequency_timer
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# Init volume envelope
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init_volume_envelope
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# Init sweep
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@frequency_shadow = @frequency
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@sweep_timer = @sweep_period > 0 ? @sweep_period : 8_u8
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@sweep_enabled = @sweep_period > 0 || @shift > 0
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@negate_has_been_used = false
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if @shift > 0 # If sweep shift is non-zero, frequency calculation and overflow check are performed immediately
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frequency_calculation
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end
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end
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else raise "Writing to invalid Channel1 register: #{hex_str index.to_u16}"
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end
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end
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end
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94
src/crab/apu/channel2.cr
Normal file
94
src/crab/apu/channel2.cr
Normal file
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@ -0,0 +1,94 @@
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class Channel2 < VolumeEnvelopeChannel
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WAVE_DUTY = [
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[0, 0, 0, 0, 0, 0, 0, 1], # 12.5%
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[1, 0, 0, 0, 0, 0, 0, 1], # 25%
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[1, 0, 0, 0, 0, 1, 1, 1], # 50%
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[0, 1, 1, 1, 1, 1, 1, 0], # 75%
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]
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RANGE = 0x68..0x6F
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def ===(value) : Bool
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value.is_a?(Int) && RANGE.includes?(value)
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end
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@wave_duty_position = 0
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# NR21
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@duty : UInt8 = 0x00
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@length_load : UInt8 = 0x00
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# NR23 / NR24
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@frequency : UInt16 = 0x00
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def step_wave_generation : Nil
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@wave_duty_position = (@wave_duty_position + 1) & 7
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end
|
||||
|
||||
def frequency_timer : UInt32
|
||||
(0x800_u32 - @frequency) * 4 * 4
|
||||
end
|
||||
|
||||
def schedule_reload(frequency_timer : UInt32) : Nil
|
||||
@gba.scheduler.schedule frequency_timer, ->step, Scheduler::EventType::APUChannel2
|
||||
end
|
||||
|
||||
def get_amplitude : Float32
|
||||
if @enabled && @dac_enabled
|
||||
dac_input = WAVE_DUTY[@duty][@wave_duty_position] * @current_volume
|
||||
dac_output = (dac_input / 7.5) - 1
|
||||
dac_output
|
||||
else
|
||||
0
|
||||
end.to_f32
|
||||
end
|
||||
|
||||
def read_io(index : Int) : UInt8
|
||||
case index
|
||||
when 0x68 then 0x3F_u8 | @duty << 6
|
||||
when 0x69 then read_NRx2
|
||||
when 0x6C then 0xFF_u8 # write-only
|
||||
when 0x6D then 0xBF_u8 | (@length_enable ? 0x40 : 0)
|
||||
else raise "Reading from invalid Channel2 register: #{hex_str index.to_u16}"
|
||||
end
|
||||
end
|
||||
|
||||
def write_io(index : Int, value : UInt8) : Nil
|
||||
case index
|
||||
when 0x68
|
||||
@duty = (value & 0xC0) >> 6
|
||||
@length_load = value & 0x3F
|
||||
# Internal values
|
||||
@length_counter = 0x40 - @length_load
|
||||
when 0x69
|
||||
write_NRx2 value
|
||||
when 0x6C
|
||||
@frequency = (@frequency & 0x0700) | value
|
||||
when 0x6D
|
||||
@frequency = (@frequency & 0x00FF) | (value.to_u16 & 0x07) << 8
|
||||
length_enable = value & 0x40 > 0
|
||||
# Obscure length counter behavior #1
|
||||
if @gba.apu.first_half_of_length_period && !@length_enable && length_enable && @length_counter > 0
|
||||
@length_counter -= 1
|
||||
@enabled = false if @length_counter == 0
|
||||
end
|
||||
@length_enable = length_enable
|
||||
trigger = value & 0x80 > 0
|
||||
if trigger
|
||||
@enabled = true if @dac_enabled
|
||||
# Init length
|
||||
if @length_counter == 0
|
||||
@length_counter = 0x40
|
||||
# Obscure length counter behavior #2
|
||||
@length_counter -= 1 if @length_enable && @gba.apu.first_half_of_length_period
|
||||
end
|
||||
# Init frequency
|
||||
@gba.scheduler.clear Scheduler::EventType::APUChannel2
|
||||
schedule_reload frequency_timer
|
||||
# Init volume envelope
|
||||
init_volume_envelope
|
||||
end
|
||||
else raise "Writing to invalid Channel2 register: #{hex_str index.to_u16}"
|
||||
end
|
||||
end
|
||||
end
|
||||
123
src/crab/apu/channel3.cr
Normal file
123
src/crab/apu/channel3.cr
Normal file
|
|
@ -0,0 +1,123 @@
|
|||
class Channel3 < SoundChannel
|
||||
RANGE = 0x70..0x77
|
||||
WAVE_RAM_RANGE = 0x90..0x9F
|
||||
|
||||
def ===(value) : Bool
|
||||
value.is_a?(Int) && RANGE.includes?(value) || WAVE_RAM_RANGE.includes?(value)
|
||||
end
|
||||
|
||||
@wave_ram = Bytes.new(WAVE_RAM_RANGE.size) { |idx| idx & 1 == 0 ? 0x00_u8 : 0xFF_u8 }
|
||||
@wave_ram_position : UInt8 = 0
|
||||
@wave_ram_sample_buffer : UInt8 = 0x00
|
||||
|
||||
# NR31
|
||||
@length_load : UInt8 = 0x00
|
||||
|
||||
# NR32
|
||||
@volume_code : UInt8 = 0x00
|
||||
|
||||
@volume_code_shift : UInt8 = 0
|
||||
|
||||
# NR33 / NR34
|
||||
@frequency : UInt16 = 0x00
|
||||
|
||||
def step_wave_generation : Nil
|
||||
@wave_ram_position = (@wave_ram_position + 1) % (WAVE_RAM_RANGE.size * 2)
|
||||
@wave_ram_sample_buffer = @wave_ram[@wave_ram_position // 2]
|
||||
end
|
||||
|
||||
def frequency_timer : UInt32
|
||||
(0x800_u32 - @frequency) * 2 * 4
|
||||
end
|
||||
|
||||
def schedule_reload(frequency_timer : UInt32) : Nil
|
||||
@gba.scheduler.schedule frequency_timer, ->step, Scheduler::EventType::APUChannel3
|
||||
end
|
||||
|
||||
def get_amplitude : Float32
|
||||
if @enabled && @dac_enabled
|
||||
dac_input = ((@wave_ram_sample_buffer >> (@wave_ram_position & 1 == 0 ? 4 : 0)) & 0x0F) >> @volume_code_shift
|
||||
dac_output = (dac_input / 7.5) - 1
|
||||
dac_output
|
||||
else
|
||||
0
|
||||
end.to_f32
|
||||
end
|
||||
|
||||
def read_io(index : Int) : UInt8
|
||||
case index
|
||||
when 0x70 then 0x7F | (@dac_enabled ? 0x80 : 0)
|
||||
when 0x72 then 0xFF
|
||||
when 0x73 then 0x9F | @volume_code << 5
|
||||
when 0x74 then 0xFF
|
||||
when 0x75 then 0xBF | (@length_enable ? 0x40 : 0)
|
||||
when WAVE_RAM_RANGE
|
||||
if @enabled
|
||||
@wave_ram[@wave_ram_position // 2]
|
||||
else
|
||||
@wave_ram[index - WAVE_RAM_RANGE.begin]
|
||||
end
|
||||
else raise "Reading from invalid Channel3 register: #{hex_str index.to_u16}"
|
||||
end.to_u8
|
||||
end
|
||||
|
||||
def write_io(index : Int, value : UInt8) : Nil
|
||||
case index
|
||||
when 0x70
|
||||
@dac_enabled = value & 0x80 > 0
|
||||
@enabled = false if !@dac_enabled
|
||||
when 0x72
|
||||
@length_load = value
|
||||
# Internal values
|
||||
@length_counter = 0x100 - @length_load
|
||||
when 0x73
|
||||
@volume_code = (value & 0x60) >> 5
|
||||
# Internal values
|
||||
@volume_code_shift = case @volume_code
|
||||
when 0b00 then 4
|
||||
when 0b01 then 0
|
||||
when 0b10 then 1
|
||||
when 0b11 then 2
|
||||
else raise "Impossible volume code #{@volume_code}"
|
||||
end.to_u8
|
||||
when 0x74
|
||||
@frequency = (@frequency & 0x0700) | value
|
||||
when 0x75
|
||||
@frequency = (@frequency & 0x00FF) | (value.to_u16 & 0x07) << 8
|
||||
length_enable = value & 0x40 > 0
|
||||
# Obscure length counter behavior #1
|
||||
if @gba.apu.first_half_of_length_period && !@length_enable && length_enable && @length_counter > 0
|
||||
@length_counter -= 1
|
||||
@enabled = false if @length_counter == 0
|
||||
end
|
||||
@length_enable = length_enable
|
||||
trigger = value & 0x80 > 0
|
||||
if trigger
|
||||
@enabled = true if @dac_enabled
|
||||
# Init length
|
||||
if @length_counter == 0
|
||||
@length_counter = 0x100
|
||||
# Obscure length counter behavior #2
|
||||
@length_counter -= 1 if @length_enable && @gba.apu.first_half_of_length_period
|
||||
end
|
||||
# Init frequency
|
||||
# todo: I'm patching in an extra 6 T-cycles here with the `+ 6`. This is specifically
|
||||
# to get blargg's "09-wave read while on.s" to pass. I'm _not_ refilling the
|
||||
# frequency timer with this extra cycles when it reaches 0. For now, I'm letting
|
||||
# this be in order to work on other audio behavior. Note that this is pretty
|
||||
# brittle in it's current state though...
|
||||
@gba.scheduler.clear Scheduler::EventType::APUChannel3
|
||||
schedule_reload frequency_timer + 6
|
||||
# Init wave ram position
|
||||
@wave_ram_position = 0
|
||||
end
|
||||
when WAVE_RAM_RANGE
|
||||
if @enabled
|
||||
@wave_ram[@wave_ram_position // 2] = value
|
||||
else
|
||||
@wave_ram[index - WAVE_RAM_RANGE.begin] = value
|
||||
end
|
||||
else raise "Writing to invalid Channel3 register: #{hex_str index.to_u16}"
|
||||
end
|
||||
end
|
||||
end
|
||||
96
src/crab/apu/channel4.cr
Normal file
96
src/crab/apu/channel4.cr
Normal file
|
|
@ -0,0 +1,96 @@
|
|||
class Channel4 < VolumeEnvelopeChannel
|
||||
RANGE = 0x78..0x7F
|
||||
|
||||
def ===(value) : Bool
|
||||
value.is_a?(Int) && RANGE.includes?(value)
|
||||
end
|
||||
|
||||
@lfsr : UInt16 = 0x0000
|
||||
|
||||
# NR41
|
||||
@length_load : UInt8 = 0x00
|
||||
|
||||
# NR43
|
||||
@clock_shift : UInt8 = 0x00
|
||||
@width_mode : UInt8 = 0x00
|
||||
@divisor_code : UInt8 = 0x00
|
||||
|
||||
def step_wave_generation : Nil
|
||||
new_bit = (@lfsr & 0b01) ^ ((@lfsr & 0b10) >> 1)
|
||||
@lfsr >>= 1
|
||||
@lfsr |= new_bit << 14
|
||||
if @width_mode != 0
|
||||
@lfsr &= ~(1 << 6)
|
||||
@lfsr |= new_bit << 6
|
||||
end
|
||||
end
|
||||
|
||||
def frequency_timer : UInt32
|
||||
((@divisor_code == 0 ? 8_u32 : @divisor_code.to_u32 << 4) << @clock_shift) * 4
|
||||
end
|
||||
|
||||
def schedule_reload(frequency_timer : UInt32) : Nil
|
||||
@gba.scheduler.schedule frequency_timer, ->step, Scheduler::EventType::APUChannel4
|
||||
end
|
||||
|
||||
def get_amplitude : Float32
|
||||
if @enabled && @dac_enabled
|
||||
dac_input = (~@lfsr & 1) * @current_volume
|
||||
dac_output = (dac_input / 7.5) - 1
|
||||
dac_output
|
||||
else
|
||||
0
|
||||
end.to_f32
|
||||
end
|
||||
|
||||
def read_io(index : Int) : UInt8
|
||||
case index
|
||||
when 0x78 then 0xFF
|
||||
when 0x79 then read_NRx2
|
||||
when 0x7C then @clock_shift << 4 | @width_mode << 3 | @divisor_code
|
||||
when 0x7D then 0xBF | (@length_enable ? 0x40 : 0)
|
||||
else raise "Reading from invalid Channel4 register: #{hex_str index.to_u16}"
|
||||
end.to_u8
|
||||
end
|
||||
|
||||
def write_io(index : Int, value : UInt8) : Nil
|
||||
case index
|
||||
when 0x78
|
||||
@length_load = value & 0x3F
|
||||
# Internal values
|
||||
@length_counter = 0x40 - @length_load
|
||||
when 0x79
|
||||
write_NRx2 value
|
||||
when 0x7C
|
||||
@clock_shift = value >> 4
|
||||
@width_mode = (value & 0x08) >> 3
|
||||
@divisor_code = value & 0x07
|
||||
when 0x7D
|
||||
length_enable = value & 0x40 > 0
|
||||
# Obscure length counter behavior #1
|
||||
if @gba.apu.first_half_of_length_period && !@length_enable && length_enable && @length_counter > 0
|
||||
@length_counter -= 1
|
||||
@enabled = false if @length_counter == 0
|
||||
end
|
||||
@length_enable = length_enable
|
||||
trigger = value & 0x80 > 0
|
||||
if trigger
|
||||
@enabled = true if @dac_enabled
|
||||
# Init length
|
||||
if @length_counter == 0
|
||||
@length_counter = 0x40
|
||||
# Obscure length counter behavior #2
|
||||
@length_counter -= 1 if @length_enable && @gba.apu.first_half_of_length_period
|
||||
end
|
||||
# Init frequency
|
||||
@gba.scheduler.clear Scheduler::EventType::APUChannel4
|
||||
schedule_reload frequency_timer
|
||||
# Init volume envelope
|
||||
init_volume_envelope
|
||||
# Init lfsr
|
||||
@lfsr = 0x7FFF
|
||||
end
|
||||
else raise "Writing to invalid Channel4 register: #{hex_str index.to_u16}"
|
||||
end
|
||||
end
|
||||
end
|
||||
|
|
@ -6,6 +6,8 @@ class CPU
|
|||
include ARM
|
||||
include THUMB
|
||||
|
||||
CLOCK_SPEED = 2**24
|
||||
|
||||
enum Mode : UInt32
|
||||
USR = 0b10000
|
||||
FIQ = 0b10001
|
||||
|
|
|
|||
|
|
@ -9,6 +9,7 @@ require "./interrupts"
|
|||
require "./cpu"
|
||||
require "./display"
|
||||
require "./ppu"
|
||||
require "./apu"
|
||||
require "./debugger"
|
||||
|
||||
class GBA
|
||||
|
|
@ -21,6 +22,7 @@ class GBA
|
|||
getter! cpu : CPU
|
||||
getter! display : Display
|
||||
getter! ppu : PPU
|
||||
getter! apu : APU
|
||||
getter! debugger : Debugger
|
||||
|
||||
def initialize(@bios_path : String, rom_path : String)
|
||||
|
|
@ -41,6 +43,7 @@ class GBA
|
|||
@cpu = CPU.new self
|
||||
@display = Display.new
|
||||
@ppu = PPU.new self
|
||||
@apu = APU.new self
|
||||
@debugger = Debugger.new self
|
||||
end
|
||||
|
||||
|
|
|
|||
|
|
@ -22,6 +22,8 @@ class MMIO
|
|||
io_addr = 0x0FFF_u16 & index
|
||||
if io_addr <= 0x05F
|
||||
@gba.ppu.read_io io_addr
|
||||
elsif io_addr <= 0xAF
|
||||
@gba.apu.read_io io_addr
|
||||
elsif (io_addr >= 0x200 && io_addr <= 0x203) || (io_addr >= 0x208 && io_addr <= 0x209)
|
||||
@gba.interrupts.read_io io_addr
|
||||
elsif io_addr >= 0x130 && io_addr <= 0x133
|
||||
|
|
@ -40,6 +42,8 @@ class MMIO
|
|||
io_addr = 0x0FFF_u16 & index
|
||||
if io_addr <= 0x05F
|
||||
@gba.ppu.write_io io_addr, value
|
||||
elsif io_addr <= 0xAF
|
||||
@gba.apu.write_io io_addr, value
|
||||
elsif (io_addr >= 0x200 && io_addr <= 0x203) || (io_addr >= 0x208 && io_addr <= 0x209)
|
||||
@gba.interrupts.write_io io_addr, value
|
||||
elsif io_addr >= 0x130 && io_addr <= 0x133
|
||||
|
|
|
|||
|
|
@ -1,15 +1,20 @@
|
|||
class Scheduler
|
||||
private record Event, cycles : UInt64, proc : Proc(Void)
|
||||
enum EventType
|
||||
DEFAULT
|
||||
APUChannel1
|
||||
APUChannel2
|
||||
APUChannel3
|
||||
APUChannel4
|
||||
end
|
||||
|
||||
private record Event, cycles : UInt64, proc : Proc(Void), type : EventType
|
||||
|
||||
@events : Deque(Event) = Deque(Event).new 10
|
||||
@cycles : UInt64 = 0
|
||||
@next_event : UInt64 = UInt64::MAX
|
||||
|
||||
def schedule(cycles : Int, proc : Proc(Void)) : Nil
|
||||
self << Event.new @cycles + cycles, proc
|
||||
end
|
||||
|
||||
def schedule(cycles : Int, &block : ->)
|
||||
self << Event.new @cycles + cycles, block
|
||||
def schedule(cycles : Int, proc : Proc(Void), type = EventType::DEFAULT) : Nil
|
||||
self << Event.new @cycles + cycles, proc, type
|
||||
end
|
||||
|
||||
@[AlwaysInline]
|
||||
|
|
@ -20,12 +25,21 @@ class Scheduler
|
|||
else
|
||||
@events << event
|
||||
end
|
||||
@next_event = @events[0].cycles
|
||||
end
|
||||
|
||||
def clear(type : EventType) : Nil
|
||||
@events.delete_if { |event| event.type == type }
|
||||
end
|
||||
|
||||
def tick(cycles : Int) : Nil
|
||||
cycles.times do
|
||||
@cycles += 1
|
||||
call_current
|
||||
if @cycles + cycles < @next_event
|
||||
@cycles += cycles
|
||||
else
|
||||
cycles.times do
|
||||
@cycles += 1
|
||||
call_current
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
|
|
@ -36,7 +50,12 @@ class Scheduler
|
|||
event.proc.call
|
||||
@events.shift
|
||||
else
|
||||
break
|
||||
if event
|
||||
@next_event = event.cycles
|
||||
else
|
||||
@next_event = UInt64::MAX
|
||||
end
|
||||
return
|
||||
end
|
||||
end
|
||||
end
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue